I. Introduction
Question Generation (QG) is designed to generate related questions based on the input data [1]. When the input data is in the form of Knowledge Graph (KG), the task is normally called Knowledge Base Question Generation (KBQG), which requires the combination of knowledge representation and Natural Language Generation (NLG) techniques [2]. The intelligent chatbot can also be more proactive by employing KBQG technique to raise questions [3]. Therefore, KBQG has attracted a surge of interests in the recent years.